The present invention relates to a liquid detergent composition especially suitable for dishwashing. Such compositions contain a nonionic surface-active agent and a gel-forming gelatin. In particular, it pertains to liquid detergent compositions designed for cleaning glassware, china, and glazed or vitreous articles that provide outstanding drainage characteristics, thus avoiding the need for towel-drying. Filming, streaking, and spotting of the washed, rinsed, and air-dried articles are thereby minimized.
The performance of a detergent composition for cleaning glasses, dishes, windows and other articles with a glazed surface is usually evaluated by the consumer in terms of shine and the absence of filming, streaking, and spotting. The liquid dishwashing detergent compositions presently on the market are designed to remove the soils from glasses, dishes, and other tableware and kitchen utensils. The detergent solution and redeposited soil residues are normally removed from the washed articles by rinsing and/or towelling the articles when they are still wet. If not rinsed and towel-dried, these residues dry upon the surfaces of the washed articles, leaving films, streaks, or spots.
Even when such articles are entirely clean but rinsed in plain water containing dissolved salts such as water hardness, spots and streaks can appear on the washed and rinsed surfaces upon evaporation of the water.
Towel-drying of washed articles, e.g., glasses and dishes, immediately after removal from the washing and rinsing solution, is undesirable from the standpoints of convenience and hygiene. Therefore, it is common practice simply to put the washed or washed and rinsed articles aside for draining and air-drying. Consequently, the cleaning efficiency of the product used, which the housewife may have visually appreciated at the end of the washing or rinsing cycle, is diminished due to the adherence of redeposited soil, residual dried detergent, and/or water hardness residues.
The cleaning of larger glazed surfaces as tiled walls also requires wiping or rinsing and wiping when still wet to avoid filming, streaking, and spotting. Wiping immediately after cleaning to avoid evaporation and consequently filming, streaking, and spotting is not always practical and requires a frequent interruption of the cleaning process. Therefore, the detergent composition used may be considered as not cleaning well because of the film, streaks, and spots left on the treated surfaces, although the soil may have been removed.
Attempts have been made to minimize the effect of detergent, soil, and/or water hardness residue deposition during air-drying by employing various additives at either the washing or rinsing stage of the cleaning cycle, by either complexing the water hardness salts, adding improved soil-suspending agents, or formulating special rinsing agents. The incorporated complexing and/or soil suspending agents in liquid detergent compositions create formulation difficulties, while the special rinsing agents have to be packed and applied separately.
Detergent compositions containing gelatin or hydrolyzed proteins and surface-active agents have been disclosed for purposes other than the prevention of film, streaks, and spots. In U.S. Pat. No. 3,548,056, issued Dec. 15, 1970, the described lotion or detergent composition contains partially degraded protein having a gel strength of zero Bloom grams to improve mildness to skin. Italian Patent Specification No. 862,247 and U.S. Pat. No. 3,704,228 disclose detergent compositions containing gelatin, but the compositions are not within the scope of the present invention with regard to composition or the benefit provided.
There is a continuing need, however, for compositions and methods which can be employed during dishwashing operations to improve the final dry appearance of washed and dried kitchen utensils and articles. If such compositions and methods are intended to be useful for conventional dishwashing soil removal operations, there is a continuing need for a compatible combination of materials which will simultaneously provide the surfactancy, sudsing, and mildness attributes of an acceptable dishwashing detergent composition as well as the anti-spotting and anti-filming benefits descibed above.
Accordingly, it is an object of the present invention to provide liquid detergent compositions which provide a clean, shiny, and spotless appearance to the surfaces of kitchen utensils or glossy surfaces such as glazed tile after such surfaces have been washed in said compositions and dried.
It is a further object of the present invention to provide aesthetically acceptable liquid detergent compositions for treating surfaces of kitchen utensils as described above, said compositions having the commercially acceptable dishwashing detergent composition attributes of proper surfactancy, sudsing, and mildness.
It has now been surprisingly found that a liquid detergent containing a small amount of water soluble gelatin having a molecular weight of at least 12,500, an iso-electric point between pH 4.5 and pH 9.2, and a gel strength of from about 25 to about 300 Bloom grams, and a nonionic surface-active detergent, provides outstanding washing and cleaning compositions especially suitable for cleaning glassware, china, and glazed or vitreous articles.